last time this happened, ad muncher said they wouldn't be able to block the ads, nor would they ever try to. Later on, ad muncher went free and stopped being actively developed or something.Adblock plus seems to be able to block them with a plugin, at least.

The changes are designed to ensure that users are safe from ad-borne security threats when watching videos, opening mobile apps or running any applications, the two Google executives blogged. Moving ads to HTTPS ensures that users will automatically have an encrypted connection with the ad servers, just like they have an encrypted connection when using Google Search and Gmail and YouTube.

-The Article

Somehow I don't recall ever hearing about MITM being an issue/factor with hostile Ads, as it's usually the Ads themselves that are foisting some scareware crap on the target. The marketing companies being constantly in a froth for money...the "screening process" (yes I'm smirking) for who gets to advertise what is total shit. Delivering malware over a "secure" connection - to me - makes about as much sense as having an attacker take a shower before they murder you.